Radiation image detection apparatus including photographic mode and irradiation detection mode, and radiation image photographing system including the same

ABSTRACT

A radiation image detection apparatus, including an image receiving unit having a two-dimensional array of a plurality of pixels that generate electrical charges when being subjected to irradiation of radiation, the plurality of pixels including a plurality of pixels for detecting an image and one or more pixels for detecting irradiation; an image data generation unit configured to generate image data based on an electrical signal output from the respective pixels for detecting the image, an irradiation detection unit configured to detect the irradiation of radiation based on the electrical signal output from the respective pixels for detecting irradiation, a communication unit that transmits the image data generated in the image data generation unit, and a control unit configured to include a plurality of control modes including a photographing mode generating the image data, an irradiation detection mode detecting the irradiation of radiation and a standby mode.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation Application of U.S. patentapplication Ser. No. 15/071,416, filed on Mar. 16, 2016, which is aContinuation Application of U.S. patent application Ser. No. 13/581,998,filed on Nov. 20, 2012, now U.S. Pat. No. 9,313,869 issued on Apr. 12,2016, which is based on Japanese Patent Application No. 2011-255308filed on Nov. 22, 2011, the entire contents of which are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a radiation image detection apparatusand a radiation image photographing system.

2. Related Art

An X-ray image photographing has been widely distributed in areas suchas, for example, medical diagnoses and a non-destructive inspection. Ina general X-ray image photographing, an X-ray is irradiated to a subjectand attenuated while being transmitted through each part of the subject.The transmitted X-ray is then detected and an X-ray image of the subjectis acquired based on the intensity distribution of the transmittedX-ray.

Recently, as for a medium for detecting an X-ray, a flat panel detector(FPD) having a two-dimensional array of pixels that generates anelectrical charge when subjected to X-ray irradiation and generating animage data based on an electrical signal output from each pixel of thepixel array has been used. In the X-ray image photographing, a so-calledan electronic cassette which is configured to accommodate the FPD in aportable case has been widely used.

Further, there is a known FPD configured to detect X-ray irradiationbased on electrical signal output from the pixel (for example, PatentDocument 1 (JP-A-2003-126072)). In the FPD disclosed in Patent Document1, all the pixels are installed to be utilized in both image acquisitionand irradiation detection, while in a FPD disclosed in Patent Document 2(JP-A-2011-174908), a pixel for detecting irradiation is installedseparately from a pixel for detecting image.

The FPD configured to detect X-ray irradiation based on electricalsignal output from the pixel does not need to be synchronized with anX-ray irradiation apparatus or a console controlling the operation ofthe X-ray irradiation apparatus and an operability is improved.

SUMMARY OF THE INVENTION

The electronic cassette is mounted with a battery and the operatingpower for the respective components of the FPD is supplied by thebattery. Therefore, it is required to reduce power consumption.

The output signal of the respective pixels is amplified by an amplifierand the amplifier for amplifying the output signal of the pixel fordetecting image is typically installed for each pixel column in atwo-dimensional array of pixels. Accordingly, a signal processingcircuit generating an image data based On the output signal of the pixelfor detecting image is installed with multiple amplifiers or analogdevices such as an A/D converter converting signals output from theamplifiers into digital data, and the operating power of the signalprocessing circuit is relatively high.

In a case where all the pixels are utilized in both image acquisitionand irradiation detection as in a FPD described in Patent Document 1,since an operating power needs to be continuously supplied to a signalprocessing circuit for generating an image data until X-ray isirradiated, there is a concern that a battery consumption may beincreased.

Meanwhile, as in a FPD described in Patent Document 2, in a case where asignal processing circuit for detecting X-ray irradiation based on anoutput signal of the pixel for detecting irradiation and the pixel fordetecting image is separately installed, very few pixels are enough fordetecting irradiation as compared to the number of the pixels firdetecting image and also very few amplifiers may be installed foramplifying the output signals of the pixel for detecting irradiation.Therefore, an operating power of a signal processing circuit fordetecting X-ray irradiation is lower than that of a signal processingcircuit for generating image data. Accordingly, although an operatingpower has been continuously supplied to the signal processing circuitfor detecting X-ray irradiation until X-ray is irradiated, powerconsumption can be reduced.

However, when a standby period becomes a relatively long time, anelectrical charge is accumulated in the pixels due to, for example, thedark current, so that the signal processing circuit needs to be drivenfor generating image data periodically in order to reset the pixel fordetecting image. In this case, regarding the supplying of the operatingpower to the signal processing circuit for generating image data, therewas a room for improvement in reducing power consumption.

An illustrative aspect of the invention is to reduce power consumptionof a radiation image detection apparatus detecting a radiationirradiation based on an electrical signal output from the pixel.

According to an aspect of the invention, a radiation image detectionapparatus, includes: an image receiving unit having a two-dimensionalarray of a plurality of pixels for detecting image and one or morepixels for detecting irradiation that generate electrical charges whenbeing subjected to irradiation of radiation: an image data generationunit configured to generate an image data based on an electrical signaloutput from the respective pixels for detecting image; an irradiationdetection unit configured to detect an irradiation of radiation based onthe electrical signal output from the respective pixels for detectingirradiation; and a control unit configured to include a plurality ofcontrol modes including a photographing mode generating an image dataand an irradiation detection mode detecting an irradiation of radiation,in which the image data generation unit includes a first amplifying unitamplifying the electrical signal output from the respective pixels fordetecting image and a data processing unit converting the electricalsignal amplified by the first amplifying unit into the image data, andis configured to separately supply operating power to each of the firstamplifying unit and the data processing unit, and the control unit,during the irradiation detection mode, stops supplying of an operatingpower to the data processing unit until the irradiation of radiation isdetected by the irradiation detection unit, and when the irradiation ofradiation is detected by the irradiation detection unit, the controlunit proceeds to the photographing mode and begins supplying theoperating power to the data processing unit.

With the configuration discussed above, it is possible to reduce powerconsumption of a radiation image detection apparatus detecting aradiation irradiation based on an electrical signal output from pixels.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view diagrammatically illustrating a configuration of anexample of a radiation image photographing system in accordance with afirst exemplary embodiment of the present invention;

FIG. 2 is a view illustrating a control block of the radiation imagephotographing system illustrated in FIG. 1;

FIG. 3 is a view illustrating a configuration of a radiation imagedetecting apparatus in the radiation image photographing systemillustrated in FIG. 1;

FIG. 4 is a view illustrating a configuration of a radiation imagedetector in the radiation image detecting apparatus illustrated in FIG.3;

FIG. 5 is a view illustrating a circuit configuration of an image datageneration unit of the radiation image detector illustrated in FIG. 4;

FIG. 6 is a view illustrating a circuit configuration of an irradiationdetection unit of the radiation image detector illustrated in FIG. 4;

FIG. 7 is a flow chart illustrating an operation flow of a console inthe radiation image photographing system illustrated in FIG. 1;

FIG. 8 is a flow chart illustrating an operation flow of the radiationimage detecting apparatus in the radiation image photographing systemillustrated in FIG. 1;

FIG. 9 is a timing chart illustrating the operation timing of therespective components of the radiation image detecting apparatus in theradiation image photographing system illustrated in FIG. 1;

FIG. 10 is a view illustrating a circuit configuration of an irradiationdetection unit in a modified example of the radiation image detectingapparatus illustrated in FIG. 3; and

FIG. 11 is a timing chart illustrating the operation timings of therespective components of a radiation image detecting apparatusillustrated in FIG. 10.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

An X-ray image photographing system 1 is largely divided into an X-rayimage photographing apparatus 2 and a console 3. The X-ray imagephotographing apparatus 2 includes an X-ray source 11 irradiating X-rayon a subject H and an electronic cassette 12 (X-ray image detectingapparatus) that detects X-ray emitted from the X-ray source 11 andhaving transmitted the subject H and generates an image data. Theconsole 3 controls operations of the respective components of the X-rayimage photographing apparatus 2 such as the X-ray source 11 or theelectronic cassette 12 based on operation of an operator.

A vertical stand 13 used in performing an X-ray image photographing instanding position and a horizontal stand 14 used in performing an X-rayimage photographing in supine position are installed in the X-rayradiography room provided with the X-ray image photographing apparatus2. The electronic cassette 12 is maintained in the vertical stand 13when performing the X-ray image photographing in standing position andmaintained in the horizontal stand 14 when performing the X-ray imagephotographing in supine position.

Further, the X-ray radiography room is provided with a support movementmechanism 15 that supports a single X-ray source 11 to be rotatableabout a horizontal shaft (direction depicted in an arrow a shown in FIG.1), to be movable in vertical direction (direction depicted in an arrowb shown in FIG. 1) and to be further movable in horizontal direction(direction depicted in an arrow c shown in FIG. 1), such that the X-rayimage photographing in standing position as well as supine position canbe performed with the single X-ray source 11. Although not illustrated,the support movement mechanism 15 includes a driving source rotating theX-ray source 11 about a horizontal shaft and a driving source moving theX-ray source 11 in a vertical direction and a driving source moving theX-ray source 11 in a horizontal direction. The driving sources arecontrolled by the console 3 based on settings manipulated by an operatorin the console 3.

The console 3 is configured as a server computer and includes a controldevice 20 constituted with CPU, ROM and RAM and the like, an inputdevice 21 through which an operator inputting a photographinginformation or issuing an exposure instruction, an image processing unit22 performing appropriate image processing on an X-ray image dataobtained by the electronic cassette 12, an image storing unit 23 storingthe X-ray image data having been subjected to the image processing, anda monitor 24 displaying the photographing information input in the inputdevice 21 or the X-ray image data generated in the image processing unit22, and an interface (I/F) 25 connected with the respective componentsof the X-ray image photographing system 1, and these componentsdescribed above are connected with each other through a bus 26.

The interface 25, through wired or wireless communication, transmits andreceives various information such as an exposure condition, which willbe described below, to and from the X-ray source 11, and transmits andreceives various information such as image data to and from theelectronic cassette 12.

FIG. 3 illustrates a configuration of the electronic cassette 12.

The electronic cassette 12 includes a FPD 30, a battery 31 supplyingoperating power to the respective components of the FPD 30 and a housing32 accommodating the FPD 30 and the battery 31. The X-rays havingtransmitted a subject transmit a ceiling plate part 32 a of the housing32 and incident on an image receiving unit of the FPD 30 accommodated inthe housing 32.

The housing 10 is formed of a material having an excellent X-raytransmissivity, and is made of such as, for example, carbon fiber,aluminum, magnesium or bio-nanofiber (cellulose microfibril), orcomposite materials, in consideration of a strength-to-weight ratio. Amaterial including, for example, a reinforced fiber resin is utilized asthe composite material and the reinforced fiber resin contains such as,for example, carbon or cellulose. Specifically, composite materials suchas a carbon fiber reinforced plastics (CFRP), a foam sandwiched by theCFRPs and a foam of which surface is coated with the CFRP are utilized.

FIG. 4 illustrates a configuration of the FPD 30.

The FPD 30 includes an image receiving unit 40 formed bytwo-dimensionally arranging a plurality of pixels 41 receiving X-ray togenerate electrical charges on an active matrix thin film transistor(TFT) array substrate.

The pixel 40 may be configured as a direct conversion type X-raydetecting device which directly converts the X-rays into the electricalcharges at a conversion layer (not illustrated) made of, for example,amorphous selenium, and accumulates the converted electrical charges ina capacitor 42 connected to an electrode of a lower portion of theconversion layer. In addition, the pixel 41 may be configured as anindirect conversion type X-ray detecting device which converts X-raysinto visible rays first using a scintillator (not illustrated) made of,for example, gadolinium oxide (Gd₂O₃), sulfated gadolinium (Gd₂O₂S) orcesium iodide (CsI), and then converts the converted visible rays intothe electrical charges using a photodiode to accumulate the convertedelectrical charges.

Among the pixel group, one or more pixels 41 are utilized to detect theX-ray irradiation and the remaining pixels 41 are utilized to detect theX-ray image. In the following, a pixel 41 for detecting the X-ray imageis referred to as an image detecting pixel 41 a and a pixel 41 fordetecting X-ray irradiation is referred to as an irradiation detectingpixel 41 b.

One or more irradiation detecting pixels 41 b may be installed in thetwo-dimensional array of pixels, but a distributed installation of aplurality of the irradiation detecting pixels 41 b is preferable. Forexample, even when material having a relatively high X-ray absorptioncapability such as bones is disposed above some of the irradiationdetecting pixels 41 b, sufficient charges are generated according to anX-ray irradiation in the irradiation detecting pixels 41 b where thehigh X-ray absorbing material is not overlapped, and the X-rayirradiation can be surely detected based on the electrical chargesgenerated in the irradiation detecting pixels 41 b.

The TFT array substrate is installed with the TFT switching devices 43corresponding to the respective pixels 41, and a gate line 44 and a dataline 45 are installed at each row and each column of the two-dimensionalarray of pixels, respectively. Each gate electrode of each TFT switchingdevice 43 is connected to the gate line 44, each source electrodethereof is connected to a capacitor 42 of the pixel 41 correspondingthereto, and each drain electrode is connected to the data line 45.

The TFT array substrate is installed with a signal line 46 connectedbetween the capacitor 42 of the pixel for detecting irradiation 41 b andthe TFT switching device 43. In the illustrated example, one pixel fordetecting irradiation 41 b is installed in each of the plurality rows,the signal line 46 is installed for each row in which the pixel fordetecting irradiation 41 b is installed, and one pixel for detectingirradiation 41 b is connected to each signal line 46. A plurality of theirradiation detecting pixels 41 b may be connected to each signal line46.

The FPD 30 includes a scanning unit 50 that controls a timing at whichelectrical charges accumulated on the respective image detecting pixels41 a are read-out, an image data generation unit 51 that generates animage data based on the electrical charges read-out from the respectiveimage detecting pixels 41 a, a communication unit 52 that transmits theimage data generated in the image data generation unit 51 to the console3, an irradiation detection unit 53 that detect the X-ray irradiationbased on the charges read-out from the respective pixel for detectingirradiation 41 b, and a battery 31, and is provided with a power sourceunit 54 supplying operating power for the respective components of theFPD 30, and a control unit 55 that controls supplying of the operatingpower to the respective components of the FPD 30 from the power sourceunit 54 and operation of the respective components of the FPD 30.

Each gate line 44 is connected to the scanning unit 50 and each dataline 45 is connected to the image data generation unit 51. The scanningunit 50 supplies a driving pulse to the TFT switching device 43 throughthe gate line 44 and turns ON the TFT switching device 43. Theelectrical charges accumulated on the pixel for detecting image 41 a towhich the TFT switching device 43 having been turned ON is connected isread-out as the TFT switching device 43 is turned ON, and is transmittedthrough the data line 45 as electrical signal and input to the imagedata generation unit 51.

Meantime, each signal line 46 is connected to the irradiation detectionunit 53. The charge accumulated on the respective irradiation detectingpixels 41 b is transmitted through the signal line 46 as an electricalsignal and input to the irradiation detection unit 53, irrespective ofON/OFF of the TFT switching device 43 corresponding to 41 b.

FIG. 5 illustrates a circuit configuration of the image data generationunit 51.

The image data generation unit 51 includes an amplifying unit 60 thatamplifies electrical signal output from the respective image detectingpixels 41 a, and a data processing unit 61 that converts the electricalsignal amplified by the amplifying unit 60 into an image data.

The amplifying unit 60 includes a plurality of variable gainpre-amplifiers (charge amplifiers) 62 installed to be corresponded toeach of the plurality of data lines 45, and each of the variable gainpre-amplifier 62 is configured to include an operation amplifier 62 a ofwhich positive input side is connected to ground, a condenser 62 bconnected in parallel between negative input side of the operationamplifier 62 a and output side thereof, and a reset switch 62 c, and thedata line 45 is connected to the negative input side of the operationamplifier 62 a. The switching ON/OFF of the reset switch 62 c iscontrolled by the control unit 55.

The data processing unit 61 includes a plurality of sample and holdcircuits 63 installed to be corresponded to the respective variable gainpre-amplifier 62, a multiplexer 64 and an analog/digital (A/D) converter65. The multiplexer 64 is configured to include switches 64 a forsequentially selecting inputs from the plurality of sample and holdcircuits 63. The sample timing of the sample and hold circuit 63 and theinput selection by the switches 64 a of the multiplexer 64 is controlledby the control unit 55.

The electronic cassette 12 is configured to make it possible toseparately supply operating power to the amplifying unit 60 and the dataprocessing unit 61, and the supplying of the operating power to theamplifying unit 60 and the data processing unit 61 is controlled by thecontrol unit 55.

When an X-ray image is detected, the driving pulse is supplied to theTFT switching device 43 through the gate line 44 from the scanning unit50, and the TFT switching device 43 is turned ON in a unit of row.Electrical charges are read-out from the pixel for detecting image 41 ato which the respective TFT switching devices 43 having been turned ONof the image detecting pixels 41 a having accumulated electrical chargeson the capacitor 42 by being subjected to an X-ray irradiation, and thecharge read-out is transmitted through the data line 45 connected to theTFT switching device 43 as an electrical signal and input tocorresponding variable gain pre-amplifier 62.

Electrical signal input to the variable gain pre-amplifier 62 isamplified with a predetermined amplification factor in the variable gainpre-amplifier 62.

The respective sample and hold circuit 63 are driven for a predeterminedtime, and a signal level of the electrical signal (voltage signal)amplified by the corresponding variable gain pre-amplifier 62 ismaintained at the sample and hold circuit 63. The signal levelmaintained at the respective sample and hold circuits 63 aresequentially selected and input to the A/D convert 65 to be convertedfrom analog to digital.

The image data generation unit 51 is connected with an image memory 56,and the image data is sequentially stored in the image memory 56.

The reset switch 62 c of the respective variable gain pre-amplifiers 62is turned ON for a predetermined time. By doing this, the chargesread-out from the pixel for detecting image 41 a and accumulated on thecondenser 62 b is discharged. The respective image detecting pixels 41 aare reset after the charges are read-out from the capacitor 42 thereofand discharged from the condenser 62 b having accumulated the read-outcharges.

As described above, a reading-out of electrical charges from the imagedetecting pixels 41 a is performed one row by one row to generate theX-ray image data.

A pixel data of the X-ray image data located at positions of therespective irradiation detecting pixels 41 b is generated by beinginterpolated using the pixel data obtained by the image detecting pixels41 a located around the irradiation pixel for detecting image 41. Thecorrection processing for the defect image may be performed, forexample, in the image processing unit 22 of the console 3.

FIG. 6 illustrates a circuit configuration of the irradiation detectionunit 53.

The irradiation detection unit 53 includes an amplifying unit 70 thatamplifies electrical signal output from the respective irradiationdetecting pixels 41 b, and a determination unit 71 that determines X-rayirradiation status based on the electrical signal amplified by theamplifying unit 70.

The amplifying unit 70 includes a plurality of variable gainpre-amplifiers (charge amplifiers) 72 installed to he corresponded toeach of the plurality of signal lines 46 and each of the variable gainpre-amplifier 72 is configured to include an operation amplifier 72 a ofwhich positive input side is connected to ground, a condenser 72 bconnected in parallel between negative input side of the operationamplifier 72 a and output side thereof, and a reset switch 72 c. Theswitching ON/OFF of the reset switch 72 c is controlled by the controlunit 55.

The determination unit 71 includes a comparator 73. The comparator 73 isconfigured to include an operation amplifier 73 a, a condenser 73 bconnected to positive input side of the operation amplifier 73 a andsupplies an electrical signal considered as a reference to the positiveinput side, and a switch 73 c connecting negative input side of theoperation amplifier 73 a and the condenser 73 b. The negative input sideof the operation amplifier 73 a is connected in parallel with therespective output terminals of the plurality of the variable gainpre-amplifiers 72 of amplifying unit 70. The ON/OFF switching of theswitch 73 c is controlled by the control unit 55, and the switch 73 c isbeing turned ON for a predetermined time, such that signal level of theelectrical signal input to the negative input side of the operationamplifier 73 a is maintained in the condenser 73 b.

The supplying of operating power to the amplifying unit 70 anddetermination unit 71 is controlled by the control unit 55 toperiodically supply operating power to the amplifying unit 70 anddetermination unit 71. Accordingly, an irradiation detecting operationis periodically performed.

The irradiation detecting operation is performed, such that theamplifying unit 70 and determination unit 71 is driven and accordingly,the charges accumulated on the capacitor 42 of the respectiveirradiation detecting pixels 41 b is transmitted through the signal line46 as electrical signal and input to corresponding variable gainpre-amplifier 72.

The electrical signal input to the respective variable gainpre-amplifiers 72 is amplified with a predetermined amplification factorby the variable gain pre-amplifier 72.

The electrical signals (voltage signal) amplified by the respectivevariable gain pre-amplifiers 72 are input to the comparator 73 of thedetermination unit 71 in parallel. The comparator 73 compares a signallevel (hereinafter, referred to as input signal level) of the inputelectrical signal with a signal level (hereinafter, referred to asreference signal level) of the electrical signal which is considered asa reference and maintained in the condenser 73 b.

Here, an input signal level of the irradiation detection operationperformed at the previous time is maintained in the condenser 73 b.After the comparison of the input signal level and the reference signallevel is completed, the switch 73 c of the comparator 73 is turned ONfor a predetermined time, and the input signal level for whichcomparison is completed is maintained in the condenser 73 b. Here, thesignal level maintained in the condenser 73 b becomes a reference signallevel for next irradiation detection operation.

When X-ray is irradiated, electrical charges depending on the receivedX-ray radiation dose are accumulated on the pixel for detectingirradiation 41 b, the input signal level to the comparator 73 becomeslarger than the reference signal level, and a detection signal(typically, signal level of any one of positive voltage and negativevoltage of operating voltage supplied to the comparator 73) is outputfrom the comparator 73.

The detection signal output from the comparator 73 is input to thecontrol unit 55 and the control unit 55 performs switching of a controlmode based on the input detection signal. The control mode will bedescribed later.

The reset switch 72 c of the respective variable gain pre-amplifiers 72is turned ON for a predetermined time and the charge accumulated on thecondenser 72 b by being read-out from the pixel for detectingirradiation 41 b is discharged. The respective irradiation detectingpixels 41 b are reset after charges are read-out from the capacitor 42thereof and discharged from the condenser 62 b having accumulated theread-out charges.

FIG. 7 illustrates an operation flow of the console 3.

First, photographing information is input in the console 3 (step S1).The photographing information includes, such as for example, a name of asubject to be photographed, a body part of the subject to bephotographed, exposure conditions of radiation (X-ray) (in the presentembodiment, a tube voltage and tube current and an exposure period whenperforming exposure with radiation (X-ray)) during X-ray imagephotographing.

When inputting of the photographing information is completed, theconsole 3 transmits control signal indicative of input completion to theelectronic cassette 12. The console 3 transmits the exposure conditionsincluded in the photographing information to the X-ray source 11 (stepS2). A preparation for exposure is performed in the X-ray source 11according to the received exposure conditions.

After the preparation for photographing such as the X-ray source 11, theelectronic cassette 12 and determination of the position of the subjectis completed, an instruction to exposure is issued from the console 3.The console 3 transmits control signal indicative of exposureinstruction to the X-ray source 11 (step S3). X-ray is irradiated fromthe X-ray source 11 according to the previously set exposure conditionsand an X-ray image data is obtained by the electronic cassette 12.

Subsequently, the X-ray image data obtained with the X-ray imagephotographing described above is transmitted from the electroniccassette 12 to the console 3 (step S4). The console 3 performs imageprocessing such as the aforementioned correction for defect pixel forthe received image data (step S5), stores the X-ray image data havingbeen conducted to the image processing in the image storing unit 23, andinstructs the monitor 24 to display the X-ray image represented from theX-ray image data (step S6).

FIG. 8 illustrates an operation flow of the electronic cassette 12.

First, a main power supply of the electronic cassette 12 is turned ON,and the respective components of the electronic cassette 12 areinitialized (step SS1). After the initialization is completed, theelectronic cassette 12 proceeds to a standby mode (step SS2). During thestandby mode, the operating power is supplied only to the communicationunit 52 and the control unit 55. and the electronic cassette 12 waitsuntil the control signal indicative of input completion of thephotographing information transmitted from the console 3 is received(step SS3).

When receiving the control signal indicative of input completion of thephotographing information, the electronic cassette 12 proceeds from thestandby mode to an irradiation detection mode (step SS4).

During the irradiation detection mode, the electronic cassette 12periodically performs a reset operation of the image detecting pixels 41a to be described below in order to discharge electrical chargesaccumulated on the respective image detecting pixels 41 a by the darkcurrent until X-ray irradiation is detected (step SS5). Further, theelectronic cassette 12 periodically performs an irradiation detectionoperation (step SS6).

When the X-ray irradiation is detected (step SS7), the electroniccassette 12 proceeds from the irradiation detection mode to aphotographing mode (step SS8) and begins the aforementioned detectionoperation of the X-ray image to generate the X-ray image data (stepSS9). The electronic cassette 12 transmits the X-ray image datagenerated with the photographing described above to the console 3 (stepSS10).

The electronic cassette 12 may be configured such that the electroniccassette 12 proceeds to, for example, the standby mode aftertransmitting of the X-ray image data is completed, and otherwise,proceeds to the irradiation detection mode first in preparation forrephotographing and after a predetermined time elapses, proceeds to thestandby mode.

FIG. 9 illustrates an operation timing of the operations of therespective components of the electronic cassette 12 while being in theirradiation detection mode and the photographing mode.

In FIG. 9, “CONTROL 1” shows “CONTROL OF SUPPLYING POWER FOR AMPLIFYINGUNIT”, “CONTROL 2” shows “CONTROL OF SUPPLYING POWER FOR DATA PROCESSINGUNIT”, “STATUS 1” shows “STATUS OF IMAGE DATA GENERATION UNIT”, “CONTROL3” shows “CONTROL OF SUPPLYING POWER FOR IRRADIATION DETECTION UNIT”,“STATUS 2” shows “STATUS OF IRRADIATION DETECTION UNIT”, a referencecharacter “A” shows “RESET OF PIXEL”, a reference character “B” shows“PAUSE”, a reference character “C” shows “ACCUMULATION OF CHARGES” and areference character “D” shows “READ-OUT OF CHARAGES”, a referencecharacter “E” shows “DETECTION” and a reference character “F” shows“PAUSE”.

During the irradiation detection mode, the irradiation detectionoperation is periodically performed. That is, the operating power isperiodically supplied from the power source unit 54 to the irradiationdetection unit 53 (amplifying unit 70 and determination unit 71)according to control by the control unit 55, and the irradiationdetection unit 53 is periodically performed. As such, the irradiationdetection operation is periodically performed and the operating power isperiodically supplied from the power source unit 54 to the irradiationdetection unit 53, so that power consumption of the irradiationdetection unit 53 can be reduced.

As the irradiation detection unit 53 is driven, the charges accumulatedon the respective irradiation detecting pixels 41 b are read-out andamplified in amplifying unit 70 and then, input to the determinationunit 71. A comparison of the input signal level with the referencesignal level maintained in the condenser 73 b of the comparator 73 isperformed in the comparator 73 of the determination unit 71.

At end of an operation period for each irradiation detection operation,the switch 73 c of the comparator 73 is turned ON for a predeterminedtime according to a record control by the control unit 55, and the inputsignal level for which comparison is completed is maintained in thecondenser 73 b. Accordingly, the input signal level is compared with aninput signal level in the previous irradiation detection operation, andthe irradiation detection operation is performed based on a differencebetween both signal levels.

Even when X-ray is not irradiated, electrical charges generated due todark currents are accumulated in the irradiation detecting pixels 41 bduring a pause period of the irradiation detection operation. Inperforming the irradiation detection operation periodically, theirradiation detection is performed based on a difference between theinput signal level and an input signal level in the previous irradiationdetection operation to exclude an influence of the charges by the darkcurrent, so that it is possible to more accurately perform theirradiation detection.

When X-ray is irradiated, since the charges depending on the receivedX-ray dose are accumulated in one or more irradiation detecting pixels41 b, a difference more than a predetermined value between the inputsignal level and a reference signal level is generated and a detectionsignal is output to the control unit 55 from the determination unit 71according to the generated difference. The control unit 55 proceed to aphotographing mode based on the input detection signal.

During the irradiation detection mode, a reset operation of the imagedetecting pixels 41 a is periodically performed. In the illustratedexample, the driving pulse is supplied to the TFT switching device 43through the gate line 44 from the scanning unit 50, and the TFTswitching device 43 is sequentially turned ON one row by one row.Electrical charges accumulated due to the dark current is read-out fromthe pixel for detecting image 41 a to which the TFT switching device 43having been turned ON and the charge read-out is accumulated on thecondenser 62 b of variable gain pre-amplifier 62 corresponding to theamplifying unit 60 through the data line 45 connected to the TFTswitching device 43. The reset switch c of the respective variable gainpre-amplifier 62 is turned ON for a predetermined time, chargesaccumulated on the condenser 62 b are discharged and the image detectingpixels 41 a is reset. The TFT switching device 43 s of a plurality ofrows or all the rows may be turned ON to reset the image detectingpixels 41 a of the plurality of rows or all the rows at once.

Here, it is not necessary to generate the image data in the resetoperation of the image detecting pixels 41 a described above and thusthe data processing unit 61 also does not need to be operated.Therefore, in the electronic cassette 12, the operating power issupplied separately to the amplifying unit 60 and the data processingunit 61 according to the control of the control unit 55, and theoperating power is supplied only to the amplifying unit 60 in theirradiation detection mode. By doing this, power consumption in theimage data generation unit 51 can be reduced.

In the electronic cassette 12, the supplying of operating power to theamplifying unit 60 is periodically performed in synchronized with thereset operation of the image detecting pixels 41 a. By doing this, powerconsumption in the image data generation unit 51 can be further reduced.

Further, it is preferable to make operation period T₁ of the irradiationdetection operation shorter than operation period T₂ of the resetoperation of the image detecting pixels 41 a. It is preferable to detectirradiation at high speed as much as possible and quickly begin theaccumulation of charges caused by the resetting of the pixels in orderto effectively utilize X-ray energy irradiated. Since the number of theimage detecting pixels 41 a is much more than that of the irradiationdetecting pixels 41 b, it is possible to rapidly detect the irradiationby making the operation period T₁ of the irradiation detection operationshorter than the operation period T₂ of the reset operation.

When the X-ray irradiation is detected by the irradiation detection unit53 and proceeds to the photographing mode, electrical charges areaccumulated on the respective image detecting pixels 41 a during theX-ray irradiation period.

After being proceeded to the photographing mode, the supplying ofoperating power to the irradiation detection unit 53 (amplifying unit 70and determination unit 71) is also stopped. Further, during the X-rayirradiation period, the charges are not read-out from the respectiveimage detecting pixels 41 a and the supplying of operating power to theimage data generation unit 51 (amplifying unit 60 and data processingunit 61) is stopped. Accordingly, power consumption can be furtherreduced.

After the X-ray irradiation is completed, operating power is supplied tothe amplifying unit 60 and the determination unit 61 of the image datageneration unit 51, the charges are read-out sequentially from therespective image detecting pixels 41 a one row by one row to generatethe X-ray image data. The generated the X-ray image data is transmittedto the console 3.

FIG. 10 illustrates a circuit configuration of the modified example ofthe irradiation image detection unit of the aforementioned electroniccassette 12.

The aforementioned electronic cassette 12 is configured such that allthe variable gain pre-amplifier 72 included in the amplifying unit 70 ofthe irradiation detection unit 53 is driven according to supplying ofoperating power to the irradiation detection unit 53 of the FPD 30.However, an electronic cassette 12 illustrated in FIG. 10 is configuredsuch that operating power may be separately supplied to the respectivevariable gain pre-amplifiers 72, and the supplying of the operatingpower to the respective variable gain pre-amplifiers 72 is controlled bythe control unit 55. The rest of the configuration is common to theaforementioned electronic cassette 12 and thus description thereof willbe omitted.

FIG. 11 illustrates an operation timing of the respective components ofthe electronic cassette 112 While being in the irradiation detectionmode and the photographing mode.

Similarly to FIG. 9, “CONTROL 1” shows “CONTROL OF SUPPLYING POWER FORAMPLIFYING UNIT”, “CONTROL 2” shows “CONTROL OF SUPPLYING POWER FOR DATAPROCESSING UNIT”, “STATUS 1” shows “STATUS OF IMAGE DATA GENERATIONUNIT”, “STATUS 2” shows “STATUS OF IRRADIATION DETECTION UNIT”, areference character “A” shows “RESET OF PIXEL”, a reference character“B” shows “PAUSE”, a reference character “C” shows “ACCUMULATION OFCHARGES” and a reference character “D” shows “READ-OUT OF CHARAGES”, areference character “E” shows “DETECTION” and a reference character “F”shows “PAUSE”.

In addition, “CONTROL 4” shows “FIRST CONTROL OF SUPPLYING POWER FORAMPLIFYING UNIT”, “CONTROL 5” shows “SECOND CONTROL OF SUPPLYING POWERFOR AMPLIFYING UNIT” and “CONTROL 6” shows “CONTROL OF SUPPLYING POWERFOR DETERMINATION UNIT”.

During the irradiation detection mode, an irradiation detectionoperation is periodically performed. However, for each irradiationdetection operation, one variable gain pre-amplifier 72 is sequentiallyselected in the amplifying unit 70 of the irradiation detection unit 53and operating power is supplied only to the selected variable gainpre-amplifier 72. Further, the operating power is supplied to thedetermination unit 71 for each irradiation detection operation.

In this case, electrical charges accumulated on the pixel for detectingirradiation 41 b connected to the signal line 46 corresponding to theselected variable gain pre-amplifier 72 is read-out, amplified in theselected variable gain pre-amplifier 72 and then, input to thedetermination unit 71. A comparison of the input signal level with thereference signal level maintained in the condenser 73 b of thecomparator 73 is performed in the comparator 73 of the determinationunit 71 to detect the irradiation based on the difference between bothsignal levels.

According to the configuration described above, it is possible to reducepower consumption of the irradiation detection unit 53 as compares witha case where all the variable gain pre-amplifiers 72 included in theamplifying unit 70 is driven for each irradiation detection operation.In this modified example, one variable gain pre-amplifier 72 is selectedin the amplifying unit 70 of the irradiation detection unit 53 to bedriven, but it is possible to obtain effect described above as long assome of the variable gain pre-amplifier 72 included in the amplifyingunit 70 are driven.

In the description as described above, a general X-ray is used as theradiation, but the present invention is not limited the X-ray andradiation other than X-ray such as a ray or γ ray may be utilized.

As described above, the radiation image detection apparatus as describedin the following (1) to (8) and the radiation image photographing systemas described in the following (9) are disclosed.

(1) A radiation image detection apparatus, includes: an image receivingunit having a two-dimensional array of a plurality of pixels fordetecting image and one or more pixels for detecting irradiation thatgenerate electrical charges when being subjected to irradiation ofradiation; an image data generation unit configured to generate an imagedata based on an electrical signal output from the respective pixels fordetecting image; an irradiation detection unit configured to detect anirradiation of radiation based on the electrical signal output from therespective pixels for detecting irradiation; and a control unitconfigured to include a plurality of control modes including aphotographing mode generating an image data and an irradiation detectionmode detecting an irradiation of radiation, in which the image datageneration unit includes a first amplifying unit amplifying theelectrical signal output from the respective pixels for detecting imageand a data processing unit converting the electrical signal amplified bythe first amplifying unit into the image data, and is configured toseparately supply operating power to each of the first amplifying unitand the data processing unit, and the control unit, during theirradiation detection mode, stops supplying of an operating power to thedata processing unit until the irradiation of radiation is detected bythe irradiation detection unit, and when the irradiation of radiation isdetected by the irradiation detection unit, the control unit proceeds tothe photographing mode and begins supplying the operating power to thedata processing unit.

(2) It is a radiation image detection apparatus according to (1), inwhich: the control unit, during the irradiation detection mode,periodically supplies the operating power to the irradiation detectionunit to be periodically operated.

(3) It is a radiation image detection apparatus according to (2), inwhich: the irradiation detection unit includes a storing unit storing asignal value corresponding to the electrical signal input, and detectsthe irradiation of radiation based on a difference between the signalvalue stored in the storing unit and the signal value corresponding tothe electrical signal input.

(4) It is a radiation image detection apparatus according to (2) or (3),in which: the image receiving unit includes a plurality of pixels fordetecting irradiation, the irradiation detection unit is installed foreach pixel for detecting irradiation or each pixel group for detectingirradiation having ones of the plurality of pixels for detectingirradiation, and the irradiation detection unit further includes: asecond amplifying unit provided with a plurality of amplifiersamplifying electrical signal output from the corresponding pixels fordetecting irradiation or the pixel group for detecting irradiation; anda determination unit detecting irradiation of radiation based on theelectrical signal amplified by the second amplifying unit, the secondamplifying unit is capable of separately supplying the operating powerto the respective amplifiers, and the control unit supplies theoperating power to ones of the amplifiers selected sequentially from theplurality of amplifiers for each operation period in a periodicoperation of the irradiation detection unit.

(5) It is a radiation image detection apparatus according to any one of(2) to (4), in which: the control unit, during the irradiation detectionmode, periodically supplies the operating power to the first amplifyingunit to be periodically operated, so that a reset operation extractingthe electrical charges generated in the respective pixels for detectingimage is periodically performed until the irradiation of radiation isdetected by the irradiation detection unit.

(6) It is a radiation image detection apparatus according to (5), inwhich: the operation period of the irradiation detection unit is shorterthan that of the reset operation of the respective pixels for detectingimage.

(7) It is a radiation image detection apparatus according to any one of(1) to (6), in which: the control unit stops supplying the operatingpower to the irradiation detection unit after the irradiation ofradiation is detected by the irradiation detection unit.

(8) It is a radiation image detection apparatus according to any one of(1) to (7) in which: the radiation image detection apparatus is aportable type.

(9) A radiation image photographing system, includes: a radiation imagedetection apparatus according to any one of (1) to (8); and a console towhich photographing information is input, in which the control unitdefines a timing at which an input of the photographing information iscompleted in the console as a starting timing of the irradiationdetection mode.

What is claimed is:
 1. An X-ray image detection apparatus, comprising:an image receiving unit having a two-dimensional array of a plurality Ofpixels that generate electrical charges when being subjected toirradiation of X-ray, the plurality of pixels including: a plurality ofpixels for detecting an image; and one or more pixels for detectingirradiation; an image data generation unit configured to generate imagedata based on an electrical signal output from the respective pixels fordetecting an image; an irradiation detection unit configured to detectthe irradiation of X-ray based on the electrical signal output from therespective pixels for detecting irradiation; a communication unit thattransmits the image data generated in the image data generation unit;and a control unit configured to include a plurality of control modesincluding a photographing mode generating image data, an irradiationdetection mode detecting whether to be a state where an irradiation ofX-ray is made or a state where an irradiation of X-ray is not made and awaiting mode to wait to receive a control signal from a console, whereinwhen the state where an irradiation of X-ray is made is detected by theirradiation detection unit during the irradiation detection mode, thecontrol unit is configured to proceed to the photographing mode, afterthe image data generated in the image data generation unit istransmitted by the communication unit, the control unit is configured toproceed to the waiting mode, and wherein there is no other mode betweenthe irradiation detection mode and the waiting mode.
 2. The X-ray imagedetection apparatus according to claim 1, wherein the control unit isconfigured to supply an operating power only to the control unit and thecommunication unit during the waiting mode.
 3. An X-ray imagephotographing system, comprising: the X-ray image detection apparatusaccording to claim 1; and a console to which photographing informationis input, wherein the control unit is configured to change to theirradiation detection mode from the waiting mode at a timing at which aninput of the photographing information is completed in the console. 4.The X-ray image detection apparatus according claim 1, wherein thephotographing mode is directly changed to the irradiation detectionmode, and after the direct change of the photographic mode to theirradiation detection mode, the irradiation detection mode is directlychanged to the waiting mode.
 5. The X-ray image detection apparatusaccording claim 1, wherein there is no other mode between thephotographic mode and the irradiation detection mode.
 6. An X-ray imagedetection apparatus, comprising: an image receiving unit having atwo-dimensional array of a plurality of pixels that generate electricalcharges when being subjected to irradiation of X-ray, the plurality ofpixels including: a plurality of pixels for detecting an image; and oneor more pixels for detecting irradiation; an image data generation unitconfigured to generate image data based on an electrical signal outputfrom the respective pixels for detecting an image; an irradiationdetection unit configured to detect the irradiation of X-ray based onthe electrical signal output from the respective pixels for detectingirradiation; a communication unit that transmits the image datagenerated in the image data generation unit; and a control unitconfigured to include a plurality of control modes including aphotographing mode generating image data, an irradiation detection modedetecting whether to be a state where an irradiation of X-ray is made ora state where an irradiation of X-ray is not made and a waiting mode towait to receive a control signal from a console, wherein when the statewhere an irradiation of X-ray is made is detected by the irradiationdetection unit during the irradiation detection mode, the control unitis configured to proceed to the photographing mode, after the image datagenerated in the image data generation unit is transmitted by thecommunication unit, the control unit is configured to proceed to thewaiting mode, and wherein the photographing mode is directly changed tothe irradiation detection mode, and after the direct change of thephotographic mode to the irradiation detection mode, the irradiationdetection mode is directly changed to the waiting mode.